I have two types of collections which use different stylesheets. Therefore I
need some kind of a flag to distinguish between them. I defined a new page
parameter:

pageparam y book

Then, I defined the corresponding cgi argument

cgiarg shortname=y argdefault=book

and in style.dm

/gsdl/web/style/style.css[y=book] {/gsdl/web/images/book_style.css}
/gsdl/web/style/style.css[y=mag] {/gsdl/web/images/mag_style.css}

However, the value of my cgi argument was not maintained between pages so I
tried adding savedarginfo=must to cgiarg. Now, after the first page of the
collection I loose collection name, ie. it is missing in links and the
collection is unusable.
Is this the right way to do it? What am I missing? If I'm wrong, does anybody
have any idea how to accomplish this custiomization?